The present subject matter relates generally to automated peritoneal dialysis (APD) devices, and potentially may be applied to other medical device applications as well, including hemodialysis applications.
Peritoneal dialysis (PD) consists of a series of cycles of filling, dwelling, and draining dialysate solution into and out of a patient's peritoneal cavity in their lower abdomen for patients with End Stage Renal Disease (ESRD). The solution is exchanged by connecting one or more dialysate solution bag(s) and associated disposable tubing to a transfer set with a shutoff pinch valve, which in turn connects to a PD catheter surgically implanted in the patient's abdomen as shown in FIG. 5. PD dialysate solution contains dextrose, icodextrin (i.e., starch-derived glucose polymer), or other molecules to create an osmotic gradient which allows toxins and excess fluids in the bloodstream to transport through the peritoneal membrane's capillary walls and into the dialysate solution. PD dialysate solution also contains electrolytes to maintain patients' normal blood composition. PD dialysate solution is currently commercially available in three different dextrose concentrations and a single icodextrin concentration.
PD therapy is performed either via gravity with dialysate bag(s) hung on a pole or elevated shelf, or with a device (cycler) to provide the motive fluid pressure/suction, also known as Automated Peritoneal Dialysis (APD). APD therapy is typically performed for 8-10 hours each night while the patient sleeps. Dialysate bags are typically hung or placed at the beginning of therapy and are typically removed after therapy completion. The patient and/or a family member or caregiver typically sets up the APD device, its associated disposable tubing set, and PD dialysate bags each night before commencing therapy.
Today, active pumping APD devices are expensive, with significant costs associated with the pump, valves, pressure sensors, and/or pneumatic manifolds, along with significant costs associated with the disposable tubing sets with cassettes to interface with said APD devices. Additionally, excessive delivery and/or suction pressures causes inflow or outflow pain during filling or draining phases for many patients. For both of those reasons, gravity-based APD devices offer benefits over current active pumping APD devices.
Today, active pumping APD devices' disposable tubing sets with cassettes are expensive. Some cassettes may require expensive ultrasonic welding or other technology to bond a rigid plastic cassette with a flexible thin plastic sheeting membrane, with costly high scrap rates associated with failed sheeting bonds. An APD device's disposable tubing set without a cassette offers cost benefits over traditional cassette-based tubing sets.
A common, serious complication of APD therapy is peritonitis. Peritonitis can occur if a patient touches the fluid path of their disposable tubing set and/or solution bag access port, resulting in touch contamination. Touch contamination can introduce bacteria or other contaminants into the sterile fluid path, thus causing an infection or inflammation of the peritoneum, known as peritonitis. Accordingly, there is a need for technology to prevent touch contamination and thus reduce the likelihood of peritonitis. Some currently available APD solution bags offer a shrouded male Luer fitting on the bag's access port to reduce the likelihood of touch contamination for APD tubing sets. However, there are no shrouded female Luer fittings which mate to the dialysate bags' shrouded male Luer fittings. Typical female Luer fittings have exposed fluid paths.
An APD device's disposable tubing set without a cassette poses a potential problem with the user loading the tubing into the hardware enclosure in the reverse orientation. Accordingly, there is a need for features to prevent the tubing set from being loaded in the reverse, upside down, backwards, or other incorrect orientation into the hardware enclosure using one or more simple, inexpensive, molded plastic parts and without requiring the usage of an expensive cassette and its associated bonded flexible membrane(s) described in the previous paragraph.
Conventionally, active pumping APD device systems, when combined with the requisite dialysate bags, are oriented in a horizontal fashion when set up in the patient's home. The APD device is typically placed on a stationary nightstand or large cart, with one or more PD dialysate bags placed next to the APD device to achieve the typical 10,000 mL-15,000 mL delivery volumes via multiple bags, each typically ranging in volume from 2,000 mL to 6,000 mL. A typical configuration might be one 5,000 mL bag placed on the APD device as a heater bag, one additional 5,000 mL bag (supply bag) placed next to the APD device, and another 2,000 mL bag (last fill bag) also placed next to the APD device. An APD device with integrated wheels and vertically-oriented dialysate bag mounting structure provides mobility benefits over current active pumping APD devices because the entire system takes up a smaller footprint on the floor and is thus more easily transported throughout the patient's home than active pumping devices mounted on a nightstand or large cart.
Patients and health care providers may desire for APD devices to be portable, both within the home and outside the home. For gravity-based devices, portability poses a problem since the machines tend to be rather tall in their therapy operational position.
Free flow of fluid from an APD device resulting in unintended Increased Intraperitoneal Volume (IIPV) can be fatal to patients. As such, there is a need for mechanisms to prevent free flow during certain single-fault conditions, such as loss of power to one or more valves which control fluid flow to or from the patient.
Conventionally, APD devices are often audibly noisy during operation. They are also prone to fluid ingress. As such, an APD device with a door over the pinch valves offers benefits over devices without said door because the door muffles the clicking noise from pinch valve actuation and provides fluid ingress protection to the pinch valves and internal components behind the pinch valve mounting wall.
Conventionally dialysate bags are often difficult to lift up to place them in the proper position required for therapy. Dialysate bag volumes may reach or exceed 6000 ml, with corresponding weights of approximately 61 Newtons (13.7 lb). These bags typically must be lifted from their original shipping container(s) (e.g. cardboard box) from approximately ground level to either approximately waist height for active pumping APD devices, or from ground level to 1.2-1.9 meters above ground level for gravity-based APD devices, in order to achieve the necessary head height required for appropriate therapeutic flow rates. In addition, the peritoneal dialysis patient population tends to skew older and more frail than the general population, thus exacerbating these potential lifting difficulties. Lifting heavy dialysate bags may cause shoulder or back problems, may lead to the user losing balance and/or falling over. These same difficulties may be experienced by caregivers who may perform setup rather than the patients themselves. Additionally, patients and caregivers in certain regions in the globe and/or female patients may have smaller statures and may not have as much strength as others. Additionally, many PD patients also suffer from other comorbidities or illnesses such as diabetes mellitus, which may further reduce the patient's ability to lift heavy objects.
Conventionally there have been no APD devices which assist the patient or caregiver in lifting PD dialysate solution bags. Existing APD devices do not provide any sort of mechanical advantage nor any other active or passive features to assist patients or caregivers in lifting heavy bags to the proper height required to perform APD therapy. As such, some physicians may be hesitant to prescribe APD therapy to a patient they believe may not possess the strength to lift the bags into place. Those patients may be forced to perform hemodialysis instead, which may not be the preferred dialysis modality for those patients.
Some manufacturers may instruct patients to use several smaller dialysate bags (e.g. 2000-2500 ml each) rather than fewer larger bags (5000-6000 ml each) for ease of lifting. However, several smaller bags are more expensive to manufacture than fewer larger bags. Additionally, several smaller bags may take up more room on the surface on which the bags are placed (e.g. table, cart, nightstand, etc).
APD patients may use different dialysate fluid concentrations within a given therapy, or from one therapy to the next. One existing APD device simply says, “CONNECT BAGS”, rather than helping identify which bag to connect to which disposable tubing set connector. In addition, although physicians and nurses may think of the bags in terms of the concentration of the osmotic agent, (e.g. dextrose concentration), patients may think of the bags in terms of the color of the bag connector associated with a given concentration, which may also correspond to the color of the tape securing the top of each dialysate box. Currently available color/concentration combinations include Yellow (1.5% dextrose), Green (2.5% dextrose), Red (4.25% dextrose), or Purple (7.5% icodextrin).
APD patients and/or their caregivers may be illiterate or have low literacy. They may not be able to read text-based prompts to properly set up, monitor, tear down, or troubleshoot their APD therapy.
Some manufacturers have attempted to mitigate the height required to lift the bags for gravity-based APD therapy by placing the bag hooks/shelves at a lower height than they would otherwise want to place them to achieve good flow rates. These approaches may be used for either active pumping or gravity-based APD devices.
If a gravity-based APD device provides a lower-than-optimal placement height for the dialysate bags, the flow rates for delivering fresh dialysate solution to the patient may be reduced. This will either result in a longer therapy duration or less effective therapeutic outcomes.
A PD therapy consists of several cycles of fill, dwell, and drain. The exchange of toxins and excess fluid from the patient's bloodstream occurs primarily during the dwell periods. If it takes longer to fill due to suboptimal dialysate bag head height, then there may be less time available for dwelling. Diffusion and osmosis occurs between the patient's peritoneal membrane and the solution dwelling in contact with that membrane, after having been filled from the APD device. Therefore, therapy is less effective if low flow rates result in less dwell time, for a given (e.g. 8 hour) total therapy time. Alternatively, low flow rates could lead to longer total therapy duration, which is not desirable since patients' lives are disrupted with therapy durations that exceed the patient's normal nocturnal sleep duration.
In some locations, AC power outages are a frequent occurrence, each potentially lasting several hours. Other locations may have frequent, short duration AC power outages and/or brownouts, each lasting a few seconds or several minutes.
Additionally, if patients want to start therapy in one room within their home while performing some activity (e.g. watching TV, cooking, studying, etc), followed by movement to their bedroom to complete therapy, there may not be AC plugs readily available in all of the locations within the home that patients may find themselves wanting to perform some or all of their APD therapy.
To date, no commercially available APD device is able to continue delivering therapy during an AC power outage.
Currently, none of the widely available, inexpensive pinch valves are capable of opening the pincher jaws if a tube is not already installed in the valve, using the manufacturer's recommended voltage. They are only able to open the pincher jaws when the solenoid is activated with a tube already installed. If the solenoid is activated via its nominal specified voltage without a tube installed, the pinch valve jaws do not open. For an APD device to use pinch valves, it is desirable for the pinch valves to open when commanded by the software, even if no tube is installed, in order to facilitate loading the tubing set into the pincher jaws. There is also a need to open the pinch valves during AC power outages. Accordingly, there is a need for opening pinch valves without tubing installed, while using a commonly available, affordable battery.
Current APD devices offer an option to drain the spent effluent into a disposable drain container, typically constructed of flexible plastic film with inlet and/or outlet ports bonded into the bag. There is a need for a reusable drain container which is not frequently discarded to reduce cost and improve the environmental impact of the extra plastic drain container typically discarded each day.
Additionally, APD users may have difficulty draining the relatively large fluid volumes that may be stored in one or more reusable or disposable drain containers if the drain containers do not contain features to facilitate easy drainage.
Some physicians will deliver to the nurse or patient a prescription written in terms of total therapy volume (Total Therapy method), thus leaving the nurse, patient, and/or APD cycler to perform the math to calculate how many cycles will be delivered. Other physicians may write a prescription in terms of number of cycles (Number of Cycles method), leaving the nurse, patient, and/or APD cycler to calculate the total therapy volume, based on the cycle fill volume and optional last fill volume.
Also, some physicians write a prescription in terms of total therapy duration (Total Therapy method), leaving the nurse, patient, and/or APD cycler to perform the math to calculate the dwell duration per cycle. Other physicians may write a prescription in terms of dwell time per cycle, leaving the nurse, patient, and/or APD cycler to perform the math to calculate the total therapy duration, based on the cycle dwell time, total volume to be filled and drained, and the estimated flow rates for filling and draining.
Some conventionally available APD cyclers only allow prescription programming via the Total Therapy method. At least one existing APD cycler allows programming via either the Total Therapy method or the Number of Cycles method, but it requires the user to choose which method they will use prior to prescription programming. Users may not know which method they need to use, which could result in selecting the wrong programming method, attempting to enter their prescribed parameters, only to later realize the user interface doesn't have the programmable option(s) they need, thus resulting in the user backing out from the programming menu and trying to program the prescription again using the alternate programming method. Users prefer to simply enter whatever information they were given by their physician or nurse, without having to select from Number of Cycles method vs. Total Therapy method.
Patients and health care providers desire for APD devices to be portable, affordable, easy to clean, and aesthetically pleasing. Accordingly, there is a need for a system that addresses problems associated with active pumping devices, APD cassettes, peritonitis, loading tubing sets, horizontal device footprint, portability, free flow/IIPV, noise, dialysate bag lifting problems, connecting the proper bag concentration, low literacy users, low flow rates, therapy efficacy, AC power outages, opening pinch valves, draining spent effluent, and therapy programming, while providing a cost effective means to deliver good dialysate flow rates with accurate volumetric measurement to encourage fast fill cycles, resulting in a safe, efficient and effective therapy.